Abstract: Semiconductor crystals, especially silicon semiconductor crystals, are doped using a solution to which there are added a silicon dioxide film forming material, a p or n doping material and organic solvent, by applying this solution to the surface of the semiconductor crystals drying and calcining while forming a cohesive, adhering coating layer, and diffusing the doping material into the semiconductor crystals in the calcining. The improvement is using as the silicon dioxide film forming components acidified solutions of partially hydrolyzed alkyl and/or polysilicates, the solutions having a pH between 2 and 6.

Abstract: A process for the production of .beta.-lithium aluminate LiAlO.sub.2, is disclosed wherein a lithium hydroxide aluminate of the formula: Li.sub.2 O . Al.sub.2 O.sub.3 . nH.sub.2 O is precipitated from aqueous solutions which contain the lithium ions and aluminum in ionogenic or elementary form at a pH value above 7. The concentration of the two metal components is at least 0.1, at most 6 g-atoms per liter, preferably 2 to 5 g-atoms per liter. The precipitation product is washed and dried and then is converted by annealing into .beta.-lithium aluminate, in the temperature range between 200.degree. C. and 800.degree. C., preferably 400.degree. C.-650.degree. C., and especially 450.degree. C.-550.degree. C. The .beta.-LiAlO.sub.2 obtained thereby has a lamellae-shaped or fine crystalline form which is converted into a needle-shaped, crystalline lithium aluminate, is obtained by the process of the invention and is suitable for the construction of electrolyte matrices.